This is one of those classic suggestions that's been brought up every now and then for years.
Just like any other magic tablet, the cost of one piece of soft clay would allow a player to use high alchemy while using a non-standard spellbook.
This would be such a lovely QoL addition, especially for those barrage slayer tasks where the 30 free alchs on the Explorer's Ring get used up within minutes.
Taking a stack of alchemy tablets to nechryals, dust devils, or even boss fights like General Graardor would help players avoid the pain of juggling loot or offloading to alts or even just letting it despawn.