I've struggled with this issue before (as seen in is this thread) and now I'm there again. Suddenly the licence was lost and I couldn't get it back, in spite of doing the Clear-Data-&-Cache on both Solid Explorer and Play Store. It still won't detect my bought license. At first I'm welcomed by a "Full version activated"-message but after pretty much exactly 9 seconds it reverts to the "UNLOCK FULL VERSION"-screen (see attatched image). And, no, the buy button does _not_ identify my license; it just give me the option to buy a new license.