What you say makes sense to me too!:
Still great though! Pay monthly leasing fees, which accumulate month after month and alone will be incredibly profitable for PCTL; and if they use the fluid they generate themselves from that leased equipment then no royalties, but for any fluid they generate that they then resell, they pay royalties on top of the monthly leasing fee. This makes sense to me, but I do not know all the details of such for certain. Just seems logical, and consistent with my experience. And here's an outlier idea, if they sell rather than lease the equipment, ongoing royalties may be paid to PCTL for any resold fluid as well. That last one, just a guess though.
I do know from my understanding of past DD that they make revenue selling equipment, leasing equipment, selling fluids; they make revenue in the form of royalties as well as licensing fees. The leasing is recurring monthly revenue, for which we've seen both 3 year and 5 year contracts at a time; and royalties and licensing fees will also be recurring. Oh, and they also have equity ownership in at least one partnership, the one I'm aware of being over in the UK. This is what comes to mind here late on a Wednesday night, but there may be more.
Bottom line, this little company, expanding into multiple countries and multiple industries, with multiple products, and multiple revenue streams, is no one trick pony, but a well diversified up and coming major growth play that won't be little much longer!
Long & Strong!